# rename-ext > changes file-extension based on mime-type ### also - removes `*?|^:"<>` characters from the file-name - reducing multiple spaces, dots, and underscores - adds rename-date suffix to ensure uniquness of the filename - strips exec-flag from non-executive types (usual leftover from FAT/NTFS) - optimizes images while at it (shows reduction size in `kb` and `%`) ## install 1. look at [install](./install.sh) file for instructions 2. adjust `PREFIX` at wish 3. make sure the final directory is on `$PATH` ## use `rename-ext /Data/Pictures/_unsorted/**/*` to only change extension and nothing else: `rename-ext --only-ext /Data/Photos/2020/*` to only print a report: `rename-ext --test-run /Data/Docs/_dump/*` ## requires - [`sd`](https://github.com/chmln/sd) – better sed - [`pngcrush`](https://github.com/Kjuly/pngcrush) – to compress PNGs - [`jpegoptim`](https://github.com/tjko/jpegoptim) – to compress JPEGs ## todo - [ ] find better determination tool for `application/octet-stream` - [ ] leverage `fd` to do recursive paralel execution if some of parameters are folders ## q&a **Q**: why not just rename files to hashes of their contents, and store original filenames in some database? **A**: good point. that database is in my case a filesystem itself.